Replace "FastNext" branding with "PragmaStack" across the project

- Updated all references, metadata, and templates to reflect the new branding, including layout files, components, and documentation.
- Replaced hardcoded color tokens like `green-600` with semantic tokens (`success`, `warning`, etc.) for improved design consistency.
- Enhanced `globals.css` with new color tokens for success, warning, and destructive states using the OKLCH color model.
- Added comprehensive branding guidelines and updated the design system documentation to align with the new identity.
- Updated tests and mocks to reflect the branding changes and ensured all visual/verbal references match "PragmaStack".
- Added new `branding/README.md` and `branding` docs for mission, values, and visual identity definition.

frontend/src/components/home/DemoCredentialsModal.tsx

@@ -68,7 +68,7 @@ export function DemoCredentialsModal({ open, onClose }: DemoCredentialsModalProp
                 className="h-8 gap-2"
               >
                 {copiedRegular ? (
-                  <Check className="h-4 w-4 text-green-600" aria-hidden="true" />
+                  <Check className="h-4 w-4 text-success" aria-hidden="true" />
                 ) : (
                   <Copy className="h-4 w-4" aria-hidden="true" />
                 )}
@@ -108,7 +108,7 @@ export function DemoCredentialsModal({ open, onClose }: DemoCredentialsModalProp
                 className="h-8 gap-2"
               >
                 {copiedAdmin ? (
-                  <Check className="h-4 w-4 text-green-600" aria-hidden="true" />
+                  <Check className="h-4 w-4 text-success" aria-hidden="true" />
                 ) : (
                   <Copy className="h-4 w-4" aria-hidden="true" />
                 )}